Aircraft gas turbofan engines operate at high temperatures and therefore, engine components such as gear boxes and bearing cavities require efficient lubricating and cooling, for example by oil circulated in an oil system of the engine. The oil however, must be cooled for circulation and re-use in the oil system. Conventionally, an air cooled oil cooler used for such a purpose may be installed in the fan bypass air stream in turbofan engines. In some conventional air cooled oil cooler installations using a bypass cooling flow, the air cooled oil cooler may be partially submerged within or outside the bypass duct annulus with ducting to guide the desired flow. Installing air cooled oil coolers inside the fan bypass duct annulus of a turbofan engine requires meeting and balancing several design objectives from aerodynamics perspectives involving multi-disciplinary integration. Compact matrix coolers entirely disposed in a bypass air duct annulus may cause flow resistance to the bypass airstream and other issues affecting engine performance.
Accordingly, there is a need to provide an improved matrix-type oil cooler assembly for turbofan gas turbine engines.